The warm temps and addition of new snow has initiated a steady cycle of size 3-3.5 avalanches out of steep, rocky terrain along the highway corridor.
The new storm slab may require several days to stabilize, stick to conservative, low consequence terrain. The possibility of avalanches stepping down to deeper weak layers persists, and would result in large destructive avalanches.
The recent 30cm of storm snow buries the Jan 12 surface layer and the Jan 3 surface hoar layer ~20cm below that. The snowpack will need some time to adjust to the new load. If triggered, the storm slab could step down to deeper layers.
The lower snowpack remains weak from cold temps in December, and includes the Nov 17 layer which consists of a facetted crust in some locations, and decomposing surface hoar near.
Be particularly cautious in steep rocky areas, with thin coverage, where the majority of the snowpack is weak and facetted.
There has been fairly continuous avalanche activity since Friday evening with numerous size 3-3.5 out of the steep terrain on Mt. MacDonald and Mt. Tupper, with some of these running over the snow sheds and full path into the creek.
Elsewhere in the Park there were several size 1.5-2.0 from Mt. Smart, Ross Peak, Mt. Abbott and Cougar Mountain.
On Wednesday, explosives training produced numerous size 1-2 avalanches in steep terrain, mostly failing on the Jan 3 surface hoar, which is now buried ~40cm. One result scrubbed to ground on a shallow rocky rib and then stepped down to the Nov 17 deep persistent layer on the slope below, with a 1 meter deep crown, resulting in a size 3.
30cm of recent storm snow buries the Jan 12 surface hoar, and the Jan 3 surface hoar is ~20cm below that. The mid-pack consists of rounding facets and is gaining strength, while the bottom of the snowpack is weak and facetted with the Nov 17 facet/crust/surface hoar. This layer is ~50cm above the ground and has become less reactive in tests, but still shows 'sudden' results.
At tree line there is ~160cm, which is 70% of an average snowpack
Sunday will be mainly cloudy with isolated flurries and sunny periods. Ridge-top winds will be light from the South with alpine temps ranging from -6 to -3. Freezing level will reach up to ~1700m.
Monday will have similar weather.
Tuesday will see increasing winds and cooler temps.
